The Common Lisp Utilities cliki page served as a collection of useful CL utilities. The idea to create a bigger package out of the small suggested packages here got momentum. You can see the result at cl-utilities. The discussion below is retained for historic purposes.

Motivated by the benefits of discussing design issues in public, possibly utilities "that everyone writes" could be canonicalized and (semi-)standardized.

ARGUMENT-LIST (name, purpose, raison d'etre up for debate) returns
the arglist of a function - useful for editor interfaces,
documentation generators etc. Code could be stolen from ILISP/SLIME/clocc-port for implementations that don't have their own.